Fuel supply system for internal combustion engines



April 16, 1963 E. A. JOHNSON FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 3 Sheets-Sheet 1 INVENTOR. ELDON A. JOHNSON ATTORNEY April 16, 1963 E. A. JOHNSON 3,035,620

FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed June 2, 1958 5 Sheets-Sheet 2 55 INVENTOR. F l G. 4. ELDON A. JOHNSON Ju s/4.6.4411

ATTORNEY April 16, 1963 E. A. JOHNSON FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Sheet 3 Filed June 2, 1958 INVENTOR. ELDON A. JOHNSON Jim/aw ATTORNEY United States Patent 3,40%,620 FUEL SUPPLY SYSTEM FGR INTERNAL (IQMBUSTEGN ENGTNES Eidon A. Johnson, St. Louis, Mo, assignor to ACE Industries, incorporated, New York, N.Y., a corporation of New Jersey Filed time 2, 1953, Ser. No. 739,268 21 Qlaiins. (@l. l58--3o.4)

This invention relates to volatile fuel supply systems for internal combustion engines. The invention consists particularly in a novel fuel supply system of the recirculating type including a relatively unrestricted carburetor fuel inlet and a fuel pumping device incorporating means for efficiently handling vapors and gaseous matter while delivering only such quantities of fuel as are being consumed by the engine.

Conventional automotive carburetors of the type having a constant level chamber with a fuel inlet controlled by a float actuatedneedle valve, have the disadvantage that the float controlled needle valve seat must be rather restricted so that the needle valve, exposed to the pressure in the fuel line, may be properly controlled by a float of reasonable size. However, such a restriction necessarily substantially impedes the discharge of fluid from the pump and fuel lines and reduces the efficiency of the pump. Consequently when the fuel lines contm'n gaseous material, as for instance, when the fuel system is exposed to relatively high temperatures and/or when the fuel has excessive, low-boiling point components, problems of vapor lock and high pressure in the fueling system result. Furthermore, the bobbing of the float, due to sing ing and tilting of the fuel in the constant level bowl, causes erratic fuel level which, in turn, materially affects the metering of fuel by the carburetor, particularly duridling and low speed operation. Also, it has proven difiicult and costly to build and maintain float actuated nee le valves and seats which are reasonably efficient and trouble-free. Still another disadvantage in conventional carburetors is that the substantial volume of fuel in the bowl, necessitated by the large float or floats, is subject to surging and tilting with consequential disturbance of the fuel level and metering.

According to the present invention, the carburetor is provided with a constant level chamber of the overflow type but Without the usual float valve in the overflow chamber, and the return of overflow to the pump is effectuated by a separate, scavenger pump designed to handle either liquids or gases or mixtures thereof. The main pump is of the more or less conventional, reciprocating diaphragm type, and its main discharge passage is controlled by a diaphragm type discharge valve. The scavenger pump can be included in the main pump body, or mounted separately, and consists of a pumping diaphragm having a hydraulic connection to the main pumping chamber. The discharge from the scavenger pump is applied to the mentioned diaphragm discharge valve in such a Way as to tend to close the discharge valve, and the discharge from the scavenger is then passed or bled through a calibrated restriction to the main pump discharge line. When the consumption of fuel by the carburetor is moderate and the scavenged fuel is relatively bubblefree, the diaphragm discharge valve will remain closed until the overflow chamber in the carburetor is exhausted. Thereafter, the application of yielding gaseous pressure to the diaphragm discharge valve permits the latter to open so that a quantity of liquid fuel will be supplied from the main pumping chamber to maintain the carburetor bowl at the proper constant level.

The diaphragm pump outlet valve serves to prevent pressure build-up in the pump inlet from affecting the 3,585,5Zd Patented Apr. 16, 1963 carburetor, and also limits the pumping stroke in accordance with engine requirements, even though the main delivery passage from the pump to the carburetor is relatively unrestricted. The periodic opening of the outlet valve, also, tends to segregate gas from liquid to thereby facilitate release of such gas through vents in the system.

In the accompanying drawings which illustrate the invention,

FIG. 1 is an elevation of an automotive chassis having an engine and novel fueling system mounted thereon.

FIG. 2 is a top view of the carburetor of the system of FIG. 1 with the air inlet horn and bowl cover removed for clearer illustration of the underlying parts.

FIG. 3 is a side elevation of the novel pump, of the system of FIG. 1, showing pump actuating parts in section.

FIG. 4 is a vertical section through the pump of FIG. 3 with the working parts shown in the cutting plane for clearer illustration.

FIG. 5 is a sectional representation, somewhat schematic, of the pump and carburetor parts of the fuel system of FIGS. 1,-4.

In FIG. 1 there is illustrated a chassis 10 having any suitable internal combustion engine 11 mounted on the forward portion thereof, and a fuel supply. tank 12 mounted at the rear. The tank is connected by tubing 13 to a mechanical fuel pump 14 mounted on the side of the crankcase 11a of engine and operated from the cam shaft of the engine as by a push rod 111) and lever 14a (FIG. 3). The pump is connected by supply tubing 15 to a carburetor 16 mounted on the engine intake manifold 17. An exhaust manifold is shown at 18.

The carburetor has'a pair of downdraft mixture conduits 2th (FIG. 2) each including an inner venturi tube 21 into which discharges a main fuel supply nozzle 22. At the side of the carburetor is a fuel supply bowl (FIGS. 2 and 5), generally indicated at 23, having parallel partitions or weirs 24 forming a central, constant level chamber 25 and side, overflow chambers 26. Within chamber 25 is a cylinder 27 for mounting an accelerating pump, and a second cylinder 28 for receiving a suction step-up device, which may be of the type shown in US. Patent 2,882,027 to Cook et al. The carburetor will also be provided with suitable choke control and idling devices. At the bottom of constant level chamber 25 are a pair of main metering orifice elements 29 connected to the main nozzles by cross passages 30. The orifice elements may be controlled by suitably operated metering rods, as shown in the abovementioned patent to Cook et al. As best shown in FIG. 5, bowl cover 3, is provided with a vent 32 and a central, inlet port 33 to which is connected main supply tubing 15 leading from the fuel pump 14.

At the bottom of the bowl is a connection 34 for a scavenging tube 35 which communicates through cross passage 36 and ports 37 with overflow chambers 26.

The pump consists of a pair of casing members 38 and 319 having flanges 4t) and 41 with inclined abutting faces which clamp the periphery of a main pumping diaphragm 42. The diaphragm is centrally clamped between washers 43 and 44 which are shaped to maintain the free flexing portion of the diaphragm in a loop or bight 45 extending into the main pumping chamber 46, as covered in aco-pending application Serial No. 456,360, filed Septernlber 16, 1954, in the names of Johnson and White now Patent No. 2,840,003 of June 24, 1958. An actuating stem 47 is centrally secured to the pumping diaphragm and its clamping washers, and is connected by suitable leverage, 14a, 11b, to an engine cam for causing intermittent motion of the diaphragm in the charging direction. The intervening pumping strokes of the diaphragm are produced by coiled compression spring 48 which bears against the upper surface of diaphragm clamping washer 43. Spring 48 serves to limit the discharge pressure of the pump in the conventional manner.

Diaphragm clamping flanges 40 and 41 are themselves clamped together and about the main pumping diaphragm by a sheet metal cup 49 suitably formed in its upper portion, as at 50, to permanently secure together the casing parts and diaphragm. Lower casing or body part 39 is generally disk-shaped and below it is a second, similarly shaped body member 51. Between body members 39 and 51 there is interposed a continuous sealing gasket or diaphragm 52. The diaphragm has flexing portions 53 and 54, to be described hereafter, and is suitably apertured for the various passages, as shown.

Upper or inner body member '39 is provided with a main pump inlet port or passage 61, main pump outlet passages 62 and 63, a cavity 64 between passages 62 and 63, and a second cavity 65 communicating with main pump chamber 46 through ports 66. Plexing portion 53 of the sealing diaphragm 52 has central washers 67 forming a main pump outlet check or discharge valve which cooperates with an annular seat 68 formed on outlet passage 62 previously mentioned. This portion 53 of the sealing diaphragm traverses cavity 64 and the other free portion 54 of the sealing diaphragm traverses cavity 65 in inner body member 39. A coiled compression spring 670 urges valve 67 closed and the other pump check valves are also provided with similar biasing springs. Valve 67 is a dilferential pressure operated means for controlling the supply of fuel to the fuel recirculating system.

The lower or outer body member 51 has a main pump inlet portion 70 which connects with tubing 13 leading from the tank and communicates past inlet check valve 71 with inlet passage portion 61 in the inner body member. Body member 51 also has an outlet passage portion 72 connected to outlet tubing 15 and forming a continuation of main pump outlet passage 63. Cavities 73 and 74, respectively, underlie and are coextensive with cavities 64 and 65 in the inner body part and the respective flexing portions 53 and 54 of the sealing diaphragm. Cavity 74 forms a scavenger pump chamber 74a while the corresponding cavity 65 in the inner body member forms scavenger pulsator chamber for transmitting pressure variations in the main pump chamber 46 to the scavenger pumping diaphragm 54. Scavenger inlet connection 75 is provided with a biased, inlet check valve 76 and is connected to overflow return tube 35 leading from the bottom of the carburetor bowl. Scavenger discharge ports 77 are controlled by biased outlet check valve 78 and communicate through cross passage 79 with regulating pressure chamber 73a and thence through passage 80 and calibrated restriction 81 to main pump discharge passage 72.

Connection 35, chamber 74a, passages 79, 73, 80, and tubing 15, all form part of a recirculating system for fuel.

The described fuel supply system operates as follows: When the engine is operated, with the pump connected to the tank and carburetor as shown, fuel is drawn from the tank into main pumping chamber 46 and then discharged through outlet passages 62, 64, 63, 72 and 15 into constant level chamber 25 at the center of the carburetor bowl. At the same time, pressure pulsations in pump chamber 46 are applied through ports 66 and pulsator chamber 65 to operate scavenger pump diaphragm portion 54 to cause the drawing of fluid from overflow chambers 26 through scavenger pump chamber 74a, regulating pressure chamber 730, and restricted passage 80 into the main pump discharge line. As long as gaseous material is being passed through the scavenger chamber, main pump outlet valve 67, 53 can yield under the influence of main pump discharge pressure applied through passage 62 to permit a full pump stroke and rapid supply of liquid fuel to the carburetor through the relatively unrestricted supply tubing 15 and its fitting 33. When the liquid fuel overflows weirs 24 into overflow chambers 26, the scavenger pump will then draw liquid which will be applied to the full undersurface of valve diaphragm 53 tending to hold pump outlet check valve 67 closed due to differential action on the valve diaphragm as well as biasing spring 67a. During normal operation, outlet check valve 67 will be open intermittently so as to maintain constant level chamber 25 full of fuel and also to maintain proper pump pressure in pump chamber 46, as determined by calibrated restriction S1 and the proportions of the diaphragm valve and outlet port 62, and restrict the pump stroke in accordance with consumption of fuel by the carburetor. Should substantial quantities of gaseous fuel or air be drawn into the scavenger pump, the consequent yielding closing pressure on pump outlet valve diaphragm 53 will permit suflicient opening of this outlet valve to provide even maximum stroke of the main pumping diaphragm, if necessary. Thus, the efilciency of the supply system is greatly increased, particularly, for the handling of gaseous material.

Normally both main pump chamber 46 and scavenger pulsator chamber 65a will be filled with a continuous body of liquid forming an actuating liquid link between main pump and scavenger diaphragms 4-5 and 54. Thus, the initial discharge movement of main pump diaphragm will be utilized in producing the pumping stroke of the scavenger diaphragm. If the scavenger is pumping bubble-free liquid, only suflicient movement of the main diaphragm will be permitted to produce a full stroke of the scavenger diaphragm. This represents the minimum, constant stroke of the main diaphragm which insures a constant circulation through the pump and carburetor bowl as long as the engine is running. Thus the pump is cooled and kept reasonably free of bubbles. This minimum delivery of the pump is increased only when the fuel consumption of the engine increases so that liquid is exhausted from the overflow and scavenger system. 'Thus, the pump acts as a metering unit, delivering fuel in proportion to consumption. Another advantage results from the fact that the main pump diaphragm will be protected from excessive back pressures. Thus, straining of the diaphragm is reduced and the drum-like thumping, previously experienced during low speed operation of conventional diaphragm type fuel pumps when the diaphragm is stretched tautly by excessive back pressures, is avoided. This is accomplished, since, although the main diaphragm will continue to reciprocate sufliciently to produce full movement of the scavenger diaphragm, no fluid will be drawn past inlet check 71, which should have greater resistance to flow than pulsator ports 66, until outlet check 67 has opened, as determined by the pressure in regulator chamber 73a, to discharge some fuel from the pump chamber. Should the pressure within chamber 46 build up during operation, for instance, because of heat, reciprocation of the main and scavenger diaphragrns would be reduced only long enough to permit bleeding off of regulator chamber pressure through calibrated restriction 81. Whereupon, discharge check 67 will open to relieve the pressure build-up in the main pump chamber. Of course, when the pump is not in operation, outlet valve spring 67a will determine maximum pressure in the main pump chamber. Any tendency to pressure build-up in fuel line 15 will be promptly dissipated into the carburetor bowl and overflow chamber without raising the fuel level in the bowl or carburetor nozzles.

Pressure build-ups, particularly surges, in line 13 between the tank and pump likewise cannot affect the level in the constant lcvel bowl. Such build-up would be applied through the scavenger diaphragm to regulator chamber 73a, thus resisting opening of discharge valve 67. Ultimately, any resulting pressure build-up in the main pump chamber would be released past valve 67, as above explained, and thence in the carburetor bowl and overflow system.

No float valve is required in the overflow chambers or the constant level chamber, thus reducing the cost and resultant source of trouble due to these parts, as used heretofore.

The invention may be modified in various respects as will occur to those skilled in the art and exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim:

1. A fueling system for internal combustion engines, said system comprising a constant level fuel bowl and an overflow chamber, a fuel pump having a first pumping chamber, a pump inlet to said first pumping chamber for connection to a source of fuel, and a pump outlet from said first pumping chamber, means forming a cavity and including a movable wall dividing said cavity into first and second pressure chambers, conduit means connecting said first pressure chamber with said pump outlet and said bowl, an outlet valve in said conduit means for controlling fuel flow through said pump outlet, said outlet valve operatively connected to said movable wall, a scavenger pump having a second pumping chamber and an inlet thereto connected to said overflow chamber and an outlet therefrom, and duct means connecting said scavenger pump outlet to said bowl and to said second pressure chamber whereby the pressure in said scavenger pump outlet acts on said movable wall in a direction tending to close said outlet valve.

2. A fuel supply system for internal combustion engines, said system comprising a constant level fuel bowl and an overflow chamber communicating therewith, a fuel pump having a first pumping chamber, a pump inlet to said first pumping chamber for connection to a source of fuel and a pump outlet from said first pumping chamber, a conduit connecting said outlet and said bowl, an outlet valve for controlling fuel flow from said pump through said conduit, means forming a pressure chamber and including a movable wall operatively connected to said valve to close said valve, and a scavenger pump having a second pumping chamber including an inlet thereto connected to said overflow chamber and an outlet therefrom communicating with said pressure chamber and said bowl whereby the pressure delivered by said scavenger pump tends to close said outlet valve.

3. A fuel supply system for internal combustion engines, said system comprising a constant level fuel bowl and an overflow chamber communicating therewith, a fuel pump having a first pumping chamber, a pump inlet to said first pumping chamber for connection to a source of fuel and a pump outlet from said first pump chamber, means forming'first and second pressure chambers, a movable wall separating said pressure chambers, conduit means connecting said pump outlet and said first pressure chamber with said fuel bowl, said pump outlet including a valve seat adjacent to said movable wall, and valve means including said movable wall cooperating with said seat to control said conduit means, a scavenger pump means having a second pumping chamber and an inlet thereto communicating with said overflow chamber and an outlet therefrom in communication with said second pressure chamber.

4. A fuel supply system for an internal combustion engine, said system comprising a fuel pump having a pumping chamber, a pump inlet to said pumping chamber for connection to a source of fuel and a pump outlet from said pumping chamber, a constant level fuel bowl and an overflow chamber communicating therewith, means forming a pair of separate pressure chambers, conduit means connecting said pair of pressure chambers to said fuel bowl, a duct connecting said pump outlet and one of said pressure chambers, a movable wall structure common to and separating said pressure chambers, a valve closing said duct and operatively connected to said wall structure for controlling fuel flow into said one pressure chamber from said pumping chamber, a scavenger pump 6. means having a pumping chamber and an inlet thereto communicating with said overflow chamber and an outlet therefrom in .communication with the other one of said pressure chambers, whereby fuel is supplied to said bowl from said fuel pump in accordance with the relative pressures applied to said movable wall structure from said fuel pump pumping chamber and said scavenger pump pumping chamber respectively.

5. A fuel supply system for an internal combustion engine, said system comprising a fuel pump having a pumping chamber, a pump inlet to said pumping chamber for connection to a. source of fuel and a pump outlet from said pumping chamber, a constant level fuel bowl and an overflow chamber communicating therewith, means forming first and second pressure chambers, conduit means connecting said chambers to said bowl, a duct connecting said pump outlet and said first pressure chamber, a movable wall structure common to and separating said chambers, a valve in said duct and operatively connected to said wall structure for controlling fuel flow from said pumping chamber to said first pressure chamber, a scavenger pump means hydraulically connected to said fuel pump for actuation therewith, said scavenger pump means; including a pumping chamber and an inlet thereto communicating with said overflow chamber and an outlet therefrom communicating with said second pressure chamber, whereby fuel is supplied to said bowl from said fuel and scavenger pumps in accordmce with relative pressures applied to said movable wall structure from said fuel pump pumping chamber and said scavenger pump pumping chamber respectively.

6. A fuel supply system for internal combustion engines, said system comprising a fuel pump having a pumping chamber, a pump inlet to said pumping chamber for connection to a source of fuel, and a pump outlet from said pumpingchamber, a constant level fuel bowl and an overflow chamber communicating therewith, means forming a cavity and including a movable wall therein forming a pair of pressure chambers, supply conduit means connecting said pump outlet to one of said pressure chambers and said bowl, said supply conduit means including a valve seat forming a portion of said pumpoutlet, said movable wall including valve structure cooperating with said valve seat to control fuel flow from said pumping chamber, a scavenger pump having a pumping chamber and an inlet thereto communicating with said overflow chamber and an outlet therefrom, a fuel passage connecting said scavenger pump outlet to the other one of said pressure chambers and to said supply conduit means, a calibrated restriction means in said fuel passage between said other pressure chamber and said supply conduit means.

7. A fuel pump comprising a body having a main pumping chamber and a scavenging pumping chamber and an inlet and an outlet for each of said pumping chambers, check valve means controlling said inlets and outlets respectively, a pressure chamber in said pumping body, said check valve means controlling said main pumping chamber outlet comprising an outlet valve and a movable wall in said pressure chamber operatively connected thereto, conduit means connecting the other side of said movable wall to said scavenging chamber outlet.

8. A fuel pump and scavenging unit comprising a body having a main pumping chamber, a reciprocable pumping wall mounted therein and a cavity adjacent said pumping chamber, a diaphragm extending across and dividing said cavity into a scavenging chamber and a pulsator chamber, conduit means connecting said pulsator chamber with said main pumping chamber for causing pumping action of said diaphragm as said movable wall reciprocates, an outlet passage from said main pumping 9. A pump and scavenger unit as described in claim 8 in which said outlet valve includes a diaphragm forming a movable wall of said pressure chamber.

10. A fuel pump and scavenging unit comprising a body having a main pumping chamber with a pumping wall movably mounted therein and a cavity adjacent to said main pumping chamber, a movable wall forming within said cavity a scavenging chamber and a pulsator chamber, passage means connecting said main pumping chamber with said pulsator chamber to cause pumping action of said movable wall upon operation of said pumping wall, an outlet passage from said main pumping chamber, an outlet valve within said outlet passage, means for controlling said outlet valve, said controlling means including a pressure chamber within said body, a diaphragm forming a movable wall of said pressure chamber and operatively connected to said outlet valve, and a conduit connecting said pressure chamber with said scavenging chamber.

11. The invention of claim 10 wherein said conduit connects said pressure chamber to said outlet passage on the other side of said outlet valve from said main pumping chamber, and means forming a restriction in said conduit between said pressure chamber and said outlet passage.

12. A fuel pump and scavenger unit comprising a body including a pumping diaphragm on one side thereof forming a part of a main pumping chamber, a pair of generally disk-shaped members, means securing said members together and to said body, one side of one of said members forming another part of said main pumping chamber, said members forming a cavity therebetween, a sealing diaphragm interposed between said disk-shaped members and having a flexing portion traversing said cavity, said diaphragm flexing portion forming a pulsating chamber and a scavenger pump chamber within said cavity, an outlet passage from said scavenger pump chamber, and an inlet duct into said scavenger chamber.

13. The invention of claim 12 wherein said securing means includes a sheet metal cup fixed to said body and enclosing said disk-shaped members.

14. A fuel pump unit comprising a casing, a pumping diaphragm, a pair of generally disk-shaped members coaxially secured together and to said casing with said pumping diaphragm between said casing and said members, the side of said member next to said diaphragm forming with said diaphragm a pumping chamber, said members forming a cavity therebetween, a sealing diaphragm interposed between said disk-shaped members and having a flexing portion traversing said cavity, said diaphragm flexing portion within said cavity forming a pair of pressure chambers, an outlet passage communicating with said main pumping chamber and one of said pressure chambers, and outlet check valve in said outlet passage including a part of said diaphragm flexing portion within said cavity, a duct leading out of the other one of said pressure chambers.

15. The fuel pump unit of claim 14 including an inlet passage for said main pumping chamber extending through both of said disk-shaped members, and an inlet check valve within said inlet passage.

16. The fuel pump unit of claim 14 wherein said securing means includes a sheet metal cup fixed to said casing and enclosing said disk-shaped members.

17. A fuel pump unit comprising a casing, a pumping diaphragm, and a pair of disk-shaped members, means coaxially securing said disk-shaped members together and to said casing with the periphery of said pumping diaphragm sealed between said casing and said members, the side of said member next to said diaphragm forming with said diaphragm a pumping chamber, said members having an inlet and an outlet passage therethrough extending into said pumping chamber, a sealing diaphragm interposed between said disk-shaped members to seal said inlet passage from said outlet passage, and an inlet valve 8 and an outlet valve in said inlet and outlet passages respectively.

18. A fuel pump and scavenger unit comprising a casing, a pumping diaphragm, a pair of disk-shaped members, means securing said disk-shaped members coaxially together and to said casing with said diaphragm between said casing and said members, the side of said member next to said diaphragm forming a main pumping chamher with said diaphragm, said members forming a pair of cavities therebetween, a sealing diaphgram interposed between said disk-shaped members and having diiferent flexing portions traversing each one of said cavities, said diaphragm flexing portion within one of said cavities forming a pair of pressure chambers, the diaphragm flexing portion within the other one of said cavities forming a pulsating chamber and a scavenger pump chamber respectively, an outlet passage communicating with said main pumping chamber and one of said pressure chambers, an outlet check valve in said outlet passage connected to said diaphragm flexing portion within said one cavity, a fluid passage between said main pumping chamber and said pulusating chamber, a duct connecting said scavenger pump chamber and the other one of said pressure chambers whereby fluid pressure in said scavenger pump chamber tends to control fuel flow through said outlet check valve, and an inlet duct into said scavenger chamber.

19. A fuel pump and scavenger unit comprising a body formed with a main pumping chamber and a first and a second cavity adjacent to said main pumping chamber, fuel pumping means within said pumping chamber, diaphragm means sealed across and dividing said first and second cavities into two different chambers, an outlet passage connecting said main pumping chamber with one of said chambers formed in said first cavity by said diaphragm means, an outlet valve in said outlet passage, means operatively connecting said outlet valve to said diaphram means within said first cavity, a fuel passage connecting said main pumping chamber with one of said chambers formed by said diaphragm means in said second cavity to provide pulsating fuel pressure to said diaphragm means within said second cavity, and a conduit connecting the othere one of said chambers formed in said second cavity to the other one of said chambers formed in said first cavity for providing fuel pressure in said first cavity to operate said valve.

20. A fuel system for an internal combustion engine, said system including a fuel supply circuit and a fuel recirculating circuit interconnected therewith, a fuel chamber, a supply connection to said fuel chamber, means forming an overflow from said chamber to predetermine the head of fuel in said chamber and including an overflow bowl and an outlet from said overflow bowl, said fuel supply circuit including a source of fuel, a main pump having a pump inlet connected to said source and a pump outlet connected with said supply connection to said fuel chamber, an outlet valve in said pump outlet, fluid pressure operative means controlling the operation of said outlet valve, said recirculating circuit including a scavenger pump having an inlet connection from said overflow bowl outlet and a discharge connection with said fuel chamber, said scavenger pump discharge connection including a fluid connection with said fluid pressure operative means to control discharge of fuel from said main pump.

21. A fuel supply system for internal combustion engines, said system comprising a constant level fuel bowl and an overflow chamber communicating therewith, a fuel pump having a first pumping chamber, a pump inlet to said first pumping chamber for connection to a source of fuel and a pump outlet from said first pumping chamber, conduit means connecting said pump outlet and said bowl and including a valve for controlling fuel flow from said pump through said conduit means, scavenging pump means forming a pressure chamber and including a movable wall operatively connected to said valve to close said valve and including a second pumping chamber, said conduit means connecting said second pumping chamber to said overflow chamber and said pressure chamber and said bowl, said conduit means including a check valve between said scavenging pump chamber and said pressure chamber and a restriction between said pressure chamber and said bowl whereby the pressure delivered by said scavenger pump tends to close said outlet valve.

References Cited in the file of this patent UNITED STATES PATENTS Mallory Sept. 2, 1941 Herbelleau Jan. 15, 1952 Rodenacker Sept. 11, 1 956 Lauck Nov. 6, 1956 Batten et al Dec. 25, 1956 Ross Dec. 31, 1957 FOREIGN PATENTS Germany Jan. 30, 1922 Germany Jan. 18, 1935 

3. A FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES, SAID SYSTEM COMPRISING A CONSTANT LEVEL FUEL BOWL AND AN OVERFLOW CHAMBER COMMUNICATING THEREWITH, A FUEL PUMP HAVING A FIRST PUMPING CHAMBER, A PUMP INLET TO SAID FIRST PUMPING CHAMBER FOR CONNECTION TO A SOURCE OF FUEL AND A PUMP OUTLET FROM SAID FIRST PUMP CHAMBER, MEANS FORMING FIRST AND SECOND PRESSURE CHAMBERS, A MOVABLE WALL SEPARATING SAID PRESSURE CHAMBERS, CONDUIT MEANS CONNECTING SAID PUMP OUTLET AND SAID FIRST PRESSURE CHAMBER WITH SAID FUEL BOWL, SAID PUMP OUTLET INCLUDING A VALVE SEAT ADJACENT TO SAID MOVABLE WALL, AND VALVE MEANS INCLUDING SAID MOVABLE WALL COOPERATING WITH SAID SEAT TO CONTROL SAID CONDUIT MEANS, A SCAVENGER PUMP MEANS HAVING A SECOND PUMPING CHAMBER AND AN INLET THERETO COMMUNICATING WITH SAID OVERFLOW CHAMBER AND AN OUTLET THEREFROM IN COMMUNICATION WITH SAID SECOND PRESSURE CHAMBER. 